Computing devices, such as notebook computers, personal digital assistants, mobile communication devices, portable entertainment devices (e.g., handheld video game devices, multimedia players), and set-top-boxes (e.g., digital cable boxes, digital video disc (DVD) players) may include user interface devices that facilitate interaction between a user and the computing device.
One type of user interface device that has become more common is a touch-sensor device or touch input device that operates by way of capacitance sensing. A touch-sensor device may be in the form of a touchscreen, touch-sensor pad, a touch-sensor slider, or touch-sensor buttons, and may include an array of one or more capacitive sensor elements. Capacitive sensing typically involves measuring a change in capacitance associated with the capacitive sensor elements to detect a presence of a conductive object. A capacitance detected by a capacitive sensor may vary depending on proximity of a conductive object relative to the touch-sensor device. The conductive object may be, for example, a stylus or a user's finger.
Capacitive sensing may include a scan operation in which an electrical signal (e.g., a current) may be generated and/or measured to detect any change of capacitance associated with the capacitive sensor elements. Such scan operations may be characterized by performance metrics such as scan-time and power consumption.